linux-kernel - [PATCH 5/5] x86-64: Map the HPET NX

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Message-Id: <33a9173b25eb5b688b0b078cc002dbbd343ae73c.1306517576.git.luto@mit.edu>
Date:	Fri, 27 May 2011 13:38:42 -0400
From:	Andy Lutomirski <luto@....EDU>
To:	Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...e.hu>,
	x86@...nel.org
Cc:	linux-kernel@...r.kernel.org, Andy Lutomirski <luto@....edu>
Subject: [PATCH 5/5] x86-64: Map the HPET NX

Currently the HPET mapping is a user-accessible syscall instruction
at a fixed address some of the time.  A sufficiently determined
hacker might be able to guess when.

Signed-off-by: Andy Lutomirski <luto@....edu>
---
 arch/x86/include/asm/pgtable_types.h |    4 ++--
 arch/x86/kernel/hpet.c               |    2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/x86/include/asm/pgtable_types.h b/arch/x86/include/asm/pgtable_types.h
index 6a29aed6..013286a 100644
--- a/arch/x86/include/asm/pgtable_types.h
+++ b/arch/x86/include/asm/pgtable_types.h
@@ -107,8 +107,8 @@
 #define __PAGE_KERNEL_NOCACHE		(__PAGE_KERNEL | _PAGE_PCD | _PAGE_PWT)
 #define __PAGE_KERNEL_UC_MINUS		(__PAGE_KERNEL | _PAGE_PCD)
 #define __PAGE_KERNEL_VSYSCALL		(__PAGE_KERNEL_RX | _PAGE_USER)
-#define __PAGE_KERNEL_VSYSCALL_NOCACHE	(__PAGE_KERNEL_VSYSCALL | _PAGE_PCD | _PAGE_PWT)
 #define __PAGE_KERNEL_VVAR		(__PAGE_KERNEL_RO | _PAGE_USER)
+#define __PAGE_KERNEL_VVAR_NOCACHE	(__PAGE_KERNEL_VVAR | _PAGE_PCD | _PAGE_PWT)
 #define __PAGE_KERNEL_LARGE		(__PAGE_KERNEL | _PAGE_PSE)
 #define __PAGE_KERNEL_LARGE_NOCACHE	(__PAGE_KERNEL | _PAGE_CACHE_UC | _PAGE_PSE)
 #define __PAGE_KERNEL_LARGE_EXEC	(__PAGE_KERNEL_EXEC | _PAGE_PSE)
@@ -130,8 +130,8 @@
 #define PAGE_KERNEL_LARGE_NOCACHE	__pgprot(__PAGE_KERNEL_LARGE_NOCACHE)
 #define PAGE_KERNEL_LARGE_EXEC		__pgprot(__PAGE_KERNEL_LARGE_EXEC)
 #define PAGE_KERNEL_VSYSCALL		__pgprot(__PAGE_KERNEL_VSYSCALL)
-#define PAGE_KERNEL_VSYSCALL_NOCACHE	__pgprot(__PAGE_KERNEL_VSYSCALL_NOCACHE)
 #define PAGE_KERNEL_VVAR		__pgprot(__PAGE_KERNEL_VVAR)
+#define PAGE_KERNEL_VVAR_NOCACHE	__pgprot(__PAGE_KERNEL_VVAR_NOCACHE)
 
 #define PAGE_KERNEL_IO			__pgprot(__PAGE_KERNEL_IO)
 #define PAGE_KERNEL_IO_NOCACHE		__pgprot(__PAGE_KERNEL_IO_NOCACHE)
diff --git a/arch/x86/kernel/hpet.c b/arch/x86/kernel/hpet.c
index bfe8f72..bf71830 100644
--- a/arch/x86/kernel/hpet.c
+++ b/arch/x86/kernel/hpet.c
@@ -71,7 +71,7 @@ static inline void hpet_set_mapping(void)
 {
 	hpet_virt_address = ioremap_nocache(hpet_address, HPET_MMAP_SIZE);
 #ifdef CONFIG_X86_64
-	__set_fixmap(VSYSCALL_HPET, hpet_address, PAGE_KERNEL_VSYSCALL_NOCACHE);
+	__set_fixmap(VSYSCALL_HPET, hpet_address, PAGE_KERNEL_VVAR_NOCACHE);
 #endif
 }
 
-- 
1.7.5.1

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